This invention relates to bearings. More particularly, this invention is a new radial bearing, or thrust bearing using a magnetic field source and a magnetic field sensor for determining the speed of a rotating race with respect to an opposed fixed race.
Current electronic speed sensors consist of two or more independent components whose sole purpose is to sense speed. Typically, a magnetic field source is pressed onto a specially prepared shaft and sensor is positioned with respect to the magnetic field source. Examples of both thrust bearings and radial bearings having a magnetic field source and a sensor for the magnetic field source are described in U.S. Pat. No. 4,875,785 granted Oct. 24, 1989 in the name of Santos, et al and entitled "Thrust Bearing With A Magnetic Field Detector". Examples of thrust bearings utilizing a magnetic field source and a sensor are described in U.S. Pat. No. 4,915,512, granted Apr. 13, 1990, entitled "Thrust Bearing with a Magnetic Sensor" filed March 24, 1989 in the name of James A. Hilby and Alfred J. Santos.
It is extremely important that the spacing or clearance between the magnetic field source and the sensor be kept constant. Therefore, it is always necessary to manufacture and assemble the various mechanical elements of the bearing under extremely high precise conditions. These requirements result in higher manufacturing cost and lower productivity.
A U.S. Pat. No. 4,572,005 dated Feb. 25, 1986 in the name of Toru Kita and entitled "Magnetostriction Torque Sensor" determines the torque of a steering shaft by sensing the alterations caused by the torque on the shaft of a magnetic field in the steering shaft. An elastic sensor holder, keeps the clearance between the steering shaft and the sensor constant. U.S. Pat. No. 4,572,005, however, does not show or suggest how the separation between the magnetic field source and the magnetic field detector used with radial or thrust bearings can be kept constant.